Study on dielectric breakdown in vacuum of TiZrV coated electrode

In electron guns, electron stimulated desorption (ESD) gas can cause troubles of flowing in dark current and occurring vacuum discharge events. Non-Evaporable getter (NEG) coating on the electrode may reduce the emission of ESD gas, thereby it could reduce dark current and vacuum discharge. In this study, we investigated how NEG coating affects dark current and vacuum breakdowns characteristics for vacuum gap by using an “in-situ experimental apparatus we carried out a series of experiments including heat treatment, dark current measurement, and high voltage breakdown testing, to be conducted without exposure to the atmosphere. The results showed that NEG anodes have a lower breakdown voltage in the early stages of conditioning than Bare anodes, a higher number of breakdown times until the breakdown voltage saturates, and a larger field enhancement factor calculated from the F-N plot. This suggests that the NEG film adhered to the cathode and promoted electron emission.